Plasticizer for cellulose derivatives



1 Patented Sept. 7, 1943 l rms'rrcrzrm FOR cELLULosE DERIVATIVES Jack'1. Thurston, cos Cob, and John M. Grim,

L Stamford, Conn., asslgnors to American Cyanamid Company, New

tion of Maine No Drawing. Application October Serial No. 413,559

' 8 Claims.

This invention relates toplasticizers for cellulose derivatives, andmore particularly to the use oi aromatic glyceryl esters ofalpha-hydroxyisobutyric acid and itshydroXy-substituted derivatives asplasticizers for cellulose derivatives.

Cellulosic compositions such as cellulose esters and ethers, which arecommonly used in the preparation of lacqueramolding materials,photographic films, and the like are characterized by the fact that inthe dry state they are excessively hard and brittle and upon subjectionto relatively slight flexure or extension they check and break. Forpurposes of overcoming this defect it .has been customary to incorporatein lacquers or varnishes containing a cellulose derivative and aVolatile solvent a substantial portion of bodies designated asplasticizers. These plasticizers impart elasticity and ductility to thedried lacquer or varnish film obtained on evaporation of the volatilesolvent. When such properties are imparted to the dried film, the lattermay then York, N. Y.', a corporacontractor expand with the surface onwhich it is applied. In this manner, cracking or peeling of the film maybe avoided and its adhesive qualities'improved. similarly, whencellulose derivatives are employed in the manufacture of moldedarticles, incorporation of substantial portions of plasticizers hasbrought about a. more rapid and in which A: is an aromatic radical andx1 and X: are hydrogen, acyl oraromatlc radicals or the in which R; ishydrdaen. an alkali metal or an aliphatic, cycloaliphatic, aromatic, or,heterocyclic radical, at least one of the X2 being the group f R v Ihave a high compatibility witharrdv plasticizing action upon cellulosiccompositions. These esters are described and claimed in the co-pendingapplication of JackT. Thurston and John M.

Grim, Serial No. 364,552, filed November 6, 1940,

and as set out in that application they may be prepared by anyof themethods ordinarily employed in the production of esters.

Among the various acyl radicals that can be used to replace the hydrogenof the hydroxyl group are the aliphaticfa-cyl radicalssuch as formyl,acetyl, propionyl, butyryl,'octanoyl, carbalkoxy, and carbaryloxy.

The 'acyl radical may also be that of a cyclo-' aliphatic acid such ascyclohexyl acetic acid, camphoric acid and the like. The acyl radicalmay likewise be anaromatic radicalsuchas those of benzoic acidorsalicylic acid; Di'carboxylic acids may also be used to'acylate the hy--droxyl groups in which case two molecules of alpha-hydroxyisobutyricacid are combined with one molecule of the dlcarboxylic acid, or themono-esters of the dicarboxylic acids may be employed in which case onemolecule ofalphahydroxyisobutyric acid will combine with one molecule ofthe mono-ester of the dicarboxylic acid. Among the variousdicarboxylicacids and mono-esters which can be'used are those such as succinic,oxalic, diglycolic, sebacic, maleic, naph thalene dicarboxylic,phthalic, chlorophthalic, nitro-phthalic, and the like. The followingether-acids may also be employed to produce acylated aromatic glyceridesofalpha-hydroxw isobutyric acids: I

. 'n-Butoxyacetic acid ClHr-OCH:CHr-0-OH::COOH (Beta-n-butoxycthoxy)acetic acid I cB o-0mcflro-cmcm-m-cmo00H (Bets-(betan-butoxyethoxy)ethoxy) acetic acid Collar-O-OHaC 0 OH Cyclohexgloxyacetic acidC4Hr-O'-CH2 Ha-O-CaHrCOOH (Beta-n-butoxyethoxy) benzolc acid.

(Beta-n-butoxyethoxyiethoxy propionic acid" symbols X1 and'hydroxyisobutyric acid is replaced by either an 'alkyl, cycl-oaliphatic,arallqll, or aryl group'and such ethers of aromatic glycerides ofalpha-hydroxyisobutyric acid have properties difiering somewhatirom thearomatic glycerides themselves; The. alkyl radicals used to replace thehydrogen may be either saturated or unsaturated and may or may notcontain substituent arethe methyl. ethyl, propyl, butyl isobutyl, octyl,as well as alkyl radical-s containing carboxylic and oxy groups in thechain, to produce compounds such as the following in which R representsa glyceryl aromatic ether radical:

and

B20201: (61191033201120 CH2CHz.O.C (CH;):. C 01.11

The hydrogen of the alpha-hydroxyl group may also be replaced byalicyclic radicals such as cyclohexanyl, methyl cyclohexanyl, etc. Thevarious aralkyl radicals may be also used to replace the hydrogen of thealpha-hydroxyl group present in alpha-hydroxyisobutyric acid such asbenzyl, phenylethyl, phenylpropyl, naphthylmethyl, diphenylmethyl,diphenylethyl, cinnamyl,

etc. V

The hydrogen of the hydroxyl group present in thealpha-hydroxy-isobutyric acid may also be replaced by groups possessingketone or aldehyde radicals. For example, halogenated ketones may bereacted with the sodium salt of the aromatic lycerides ofalph'a-hydroxyisobutyric acid to split oflsodium chloride and substitutethe ketone radical in place of the hydrogen of the hydroxyl group. Forexample, when chloroacetone is reacted as described above the iollowinscompound is produced:

The corresponding aromatic ketones may be used instead or acetone.Whenchlorinated aldehydes are employed the aldehyde radical replaces thehydrogen in the hydroxyl oup.

The carbonic acid esters of the aromatic glycerides ofalphahydroxyisobutyric acid can be prepared by reacting the aromaticglyceride, with,

such as cellulose nitrate; with single organic esters of cellulose sucha cellulose acetate, cellulose propionate, cellulose butyrate andcellulose stearate: with mixed organic acid esters of cellu-- lose suchas cellulose acetate-stearate, cellulose acetate-propionate, celluloseacetate-butyrate, cellulose acetate-lactate, and cellulose acetatetartrate; with mixed inorganic and organic acid esters of cellulose suchas cellulose nitroacetates; and with cellulose ethers such as ethylcellulose and benzyl cellulose.

The aromatic glyceryl esters of alpha-hydroxyisobutyric acid and itshydroxy-substituted degroups. Included in this group of alkylradicalsrivatives may be used alone or in admixture with other plasticizers orsoftening agents such as ibutyl phthalate, camphor and the like. Theyare resistant to heat, light, and water and are good solvents for poorlymiscible material such as trijunction with the following specificexamples for example, ethyl chloroformate to produce the Variou metalradicals may be used to replace the hydrogen 'on the hydroxy group orthe esters and particualrly active metals such as the alkali metalssodium and potassium. produced by adding sodium or potassium tothearomatic glycerides o! alpha-hydroxyisobutyric acid in, an inert solventand refluxing. In some These salts are cases it is more desirable toprepare the sodium or potassium salts by reacting the aromatic ester ofalpha-hydroxyisobutyric acid with the metallic alkoxides in an inertsolvent such as toluene and remove the alcohol by distillation. A

Y The plasticizers of the present invention are compatible with andtherefore may be compounded with inorganic acid esters of cellulosedenotes complete miscibility:

IsobutymtmCelmion derivative 1 Cellulose derivative Ethyl 0o 00 0oCellulose lcetobutyrate oo 00 0o Cellulose acctopropionate co co coCellulose mate co co 0o which are for the purpose of illustration onlyand are not to be construed as limited exact details set forth:

- EXAMPLE 1 25% and 50% concentrations of (1) cresylglycerylmono-alpha-hydroxyisobutyrate, (2) cresylglyceryldi-alpha-hydroxyisobutyrate, (3) dicresylglycerylalpha-hydroxyisobutyrate, and (4) diphenylglycerylalpha-hydroxyisobutyrate were mixed with 20% solutions of nitrocellulosein a solvent comprising by volume 4 parts toluene, 3 parts ethylacetate, 2 parts butyl acetate and 1 part butyl alcohol. The resultingcompositions were poured onto glass and the films examined immediatelyafter drying. The data'obtained are as follows:

Cresylalyceryl mom-alpha-hvdroxyisobutyrate A. Compatibilitu.Mixturescontaining varying proportions of cresylglycerylmono-alpha-hydroxyisobutyrate and solutions of cellulose derivativeswere poured onto glass and the films examined after drying for one hourat F. The results, based on solutions and films, are indicated in thefollowing table where the symbol n is evident from the above data thatcresyllyceryi mono-alpha-hydroxyisobutyrate is com- Patiole with eachof-- the cellulose derlvativesin- B. Tensile strengths-Tensile strengthsof mixto the solvent comprising stantially equally effective as tures ofcresylslyceryl mono-alpha-lrvdroxyisw butyrate and 20% solutions ofnitrocellulose in a 1 part butyl alcohol in the preparation of 1:9 and25:75 were compared with those of dibutyl phthalate and nitrocellulosein the same proportions. The results are as follows:

Film Film Film Tensile Elonthickness width strength gationCresylglyceryl mono-alphahydroxylsobutyrate and Inches Inches. Elva/tn.Percent mtrocellulose-1:0 0.0011 0.5 9,040 2.5 Dibutyl phthalete andnitrocellulose-1:0 0.001 0.5 9,580 3.0 Cresylglycerylmono-alphahydroxyisobutyrate and v nitrocellulose-2.515. 0. 0012 0. 5 9,010 4. Dibutyl phthalete and nitrocellulose-2.52715 0. 0011 0. 8, 380 4.0

glyceryl mono-alpha-hydroxyisobutyrate and 61- butyl phthalate. Thecomposition of the enamels was as follows: 7

Parts by weight Titanium dioxide 100 20% nitrocellulose in solventcomprising by volume 4 parts toluene, 3 parts ethyl acetate, 2 partsbutyl acetate and 1 part butyl alcohol 100 Phthalic glyceride resinmodified with coconut and cottonseed oil fatty acids 150 Plasticlzer 40Two coats of the enamels were sprayed on bare steel panels and airdried. Sward hardness determinations were then made with the followingresults:

Air Plasticizer 1 hr. dried 6 hrs. 48 hrs.

3 hrs.

Cresylglyceryl mono-alpha-hydroxyisobutyrate 4 '8 20 Dibutyl phthalete10 18 2 24 Initially, the cresylglyceryl mono-alpha-hydroxyisobutyrateretarded the drying of the enamels in comparison with dibutyl phthalatebut after 48 hours both were very similar in their degree of hardness,the. cresylglycerylmonoalpha-hydroxy'isobutyrate showing slightsuperiority.

Examnn 3 Dicresylglyccryl' alpha hydroxyisobutumtc A.Compatibilitu-Mixtures containing varying proportions ofdicresylglyceryl alpha-hydroxyisobutyrate and solutions of cellulosederivatives were poured onto glass and xamined the films e after dryingfor one hour at 150 F. The results,

by volume 4 parts toluene. 3 parts ethyl acetate, 2 parts butyl acetateand t .3 based on both solutions and films, are indicated in thefollowing table where the symbol denotes complete miscibility:

Isobutyrate: Cellulose derivative Cellulose derivative O0 O0 O0Celluloscaoetate Slightly i 11 c o m patible.

- n. Tensile strength-Tensile strengths of mixtures of dicresylglycerylalpha-hydroxyisobutyrate and solutions of nitrocellulose in a solventcomprising by volume 4 parts toluene, 3 parts ent invention aregreaterethyl acetate, 2 parts butyl alcohol inthe proportions of 1:9 and2.5:7.5 were compared with those'of dibutyl phthalate and nitrocellulosein the same proportions. The results are as follows:

Film Film Tensile Elongl thickness width strength ationDlcresylglycerylal bah droxyisobutyrateansnitr r icel- Inches InchesLba/in. Per cent lulose-lii) 0.001 0.5 10,200 2.0 Dibutyluphthalate andni- Y trooell ace-1:0 0.001 0.5 9, 580 3.0 Dicresylgly arylalpha-hydroxyiso utyrate and ni-' trocellulose2.5:7.5 0.0011 0.5 0,1403.0 Dibutyl phthalate and nitro- In both proportions, the tensilestrengths of the films containing the plasticizer of the presthan ofthose containing dlbutyl phthalate. therefore, in view of the slightlybetter per cent elongation of the dibutyl phthalate films, thatdicresylglyceryl alpha-hydroxyisobutyrate are substantially equallyefiectlve as plasticizing agents for nitrocellulose.

C. Hardness.--Two white enamels were made containing each of *the twoplasticizers: dicresylglyceryl alpha-hydroxyisobutyrate and dibutylphthalate. The composition of the enamels was the same as in Example 2,part C.

Two coats of the enamels were sprayed on bare steel panels and airdried. Sward hard-, ness determinations were then made with thefollowing results:

Air Plastlcizer 1 hr. dried 6 hrs. 48 hrs.

- 3 hrs.

Dicresylglyceryl alphahydroryisobu 4 8 10 22 Dibutyl phthalate 10 18 2224 As in the case, of cresylglyceryl mono-alphahydroxyisobutyrate, theenamel film containing dicresylglyceryl alpha-hydroxyisobutyrate wasslower drying but after 48 hours, both films were very similar in theirdegree of hardness. Dicresylglyceryl alpha-hydroiwisobutyrate isslightly inferior in this respect to cresylglycerylmono-alpha-hydroxyisobutyrate.

Similarly, the aromatic glyceryl esters of alpha-alkoxy-isobutyric andalpha-acyloxyisobutyric acids may be incorporated with cellulosederivatives to produce, a plasticized product. Specifically,phenylglyceryl, di-alpha-ethoxylsobutyrate, cresylglycerylmono-alpha-methoxybutyl acetate and 1 part It may be concluded;

isobutyrate, diphenylglyceryl alpha-acetony-iso- -hutyrat'e,di-cresylglyceryl. alpha-propionoxymolding compositions, photographicfilm, artificial silk, coating composition, laminated articles, etc. rWe claim:

1, A composition of matter comprising a' cellulose derivative selectedfrom the group consisting of cellulose ester and cellulose ethers and asa plasticizer therefor a compound havingthe following general formula:

in which Ar is an aromatic'radical, and X1 and X: are members of thegroup consisting of hydrogen, acyl, aromatic radicals, and the group i"t on;

I I a in which R is a member of the group consisting of hydrogen, alkalimetals, aliphatic, cycloaliphatic, aromatic, and heterocyclic radicals,at least one of .the symbols X1 and X2 representing the radical v I R r2. Acomposition of mattercomprising a cel lulose derivative selectedfrom the groupconsisting of cellulose esters and cellulose ethers and asa plasticizer therefor an aromatic glyc-, eride ofalpha-hydroxyisobutyric acid.

3. A composition of matter comprising a celthe following generalformula:

sisting of cellulose esters and cellulose ethers and as a plasticizertherefor a compound having in which Ar represents an aromatic radical.

4. A composition of matter comprising a cellulose derivative selectedfrom the group consisting of cellulose esters and cellulose ethers andas a plasticizer therefor acompound having the following generalformula:

in which Ar represents an aromatic radical.

5. Acomposition of matter comprising a cellulose derivative selectedfrom the group consisting of cellulose esters and cellulose ethers andas a'plasticizer therefor'an aromatic glyceride 6. A composition ofmatter comprising a cellulosederivat ive selected from the groupconsisting of cellulose. esters and cellulose ethers and as aplasticizer therefor an aromatic glyceride of an alpha-acyloxyisobutyricacid.

7. A composition of matter comprising a cellulose derivative selectedfrom the group consistand as a plasticizer therefordi-cresylglyceryllulose derivative selected from the groupconalpha-hydroxyisobutyrate.

' JACK T. 'I'HU'RSTON.

JOHN M. GRIM.

f Sisal) CERTIFICATE OF coR'REc'I'IoN.

Patent No.. 2,5'29',015

' JACK T. mnunsrron, ET AL.

.11: is herebj c'e rtif id that error appears in the printer;specificatiqn dfithe abovenumbgb'ed pate'n t' requiring .cgrrection asfbliov'vs: Page 1,. s ecand V that the s aid Letter: Pageant hou'ld beread with tfiia ,cdrretion there -j i n 'thaj: tha same ma c onfcrm tothis recorc} 61' the case -Pa;teht -Qff-ice;.

" 'si hemand' sealed thi 26th day of octobe z 'A. 0L -,1 9h '5,

September 7,191+}.

